A lens used in connection with gonioscopy, i.e., the viewing of the periphery of the anterior chamber of the eye, is known as a gonio lens or gonioscope. A gonio lens generally includes a contact lens element and one or more mirrors. The contact lens element has an optical axis and a concave contact surface that conforms to the anterior surface of the cornea of an eye. The contact lens element also has a viewing surface that is offset in an anterior direction from the contact surface. At least one mirror is arranged with its planar surface angled away from the optical axis of the contact lens element in an anterior direction. When the contact lens element is positioned on the eye, the mirrors reflect the light from the periphery of the anterior chamber of the eye into the direction of the observer, typically via a microscope for necessary magnification.
For example, using a gonio lens, the observer can visually assess inflammation or structural defects in the trabecular meshwork and related adjacent structures in the eye. As another example, using a gonio lens that is configured for the dual purposes of viewing and treating an eye, such as an iridotomy goniolaser lens and a trabeculoplasty goniolaser lens (e.g., a Selective Laser Trabeculoplasty lens or SLT lens), the observer may assess the trabecular meshwork before, during, and after the treatment with laser energy to thereby assess the efficacy of the treatment.
As mentioned above, some lenses may include a plurality of mirrors, such as the Ocular Three Mirror Universal, manufactured by Ocular Instruments, Inc., of Bellevue, Wash., wherein the mirrors are circumferentially spaced respectively 120° apart and are mounted at different angles of inclination, such as 59°, 67°, and 73°. Each different mirror angle allows the user to inspect and evaluate different portions of the eye. However, it should be appreciated that some lenses have a plurality of mirrors all having the same angle of inclination, such as the Ocular Posner Diagnostic and Surgical Gonio lens, also manufactured by Ocular Instruments, Inc., which helps reduce the need to rotate the mirror. As another example, the lens may include a single mirror, such as the Ocular Magna View Gonio, also manufactured by Ocular Instruments, Inc.
The selection and position of the specific mirror to be used during an evaluation depends upon the portion of the eye that needs to be evaluated. The selected mirror is generally positioned opposite the area to be evaluated. For example, if the 12 o'clock position of the peripheral retina needs to be evaluated and a mirrored lens is being utilized, an angled mirror can be positioned at the 6 o'clock position of the retina so as to view the affected area.
Whether in a multiple mirror lens or a single mirror lens, it may be necessary to rotate the lens up to 360 degrees to examine the entire retina or other portions of the eye or to conduct a full treatment on the entire eye. Manipulation and positioning of the mirror at the appropriate location relative to the retina is generally accomplished by manually rotating the entire lens device on the eye of the patient until the selected mirror is located in the proper position. This orientation is obtained by rotating the lens between the forefinger and thumb of the user so that the lens is 180° opposite the area to be evaluated. Rotation of the lens can be accomplished with one or two hands depending upon the user.
Devices designed for assisting users with rotation of a contact lens relative to a patient's eye have been developed. For example, U.S. Pat. No. 6,183,085, issued to Roggy et al., is generally directed to an annular peripheral member or jacket for a lens that rotates relative to the lens housing. The rotating jacket includes a projection and groove system that maintains the rotating jacket on the lens housing, but allows for free unfettered rotational movement of the jacket relative to the housing.